Heating of fluids



Jfs. ALTHER HEATING OF FLUIDS Filed Aug. 10, 1933 2 Sheets-Sheet 1 Feb.4, 1936.

Feb. 4, 1936.

J. G. ALTHER HEATING OF FLUIDS Filed Aug. 10, 1933 2 Sheets-Sheet 2 I Il l l I I I I I I I I I I I I II III Patented Feb. 4, 1936 PATENT:oFrlcs HEATING 0F, FLUIDS Joseph G. .Alther, Chicago, 111., assignor toUniversal Oil Products Company, Chicago, 111., a corporation of DelawareI Application August 10, 1933, Serial No. 684,507

8 Claims.

This invention refers to an improved method and means for heatingfluids, and in one preferred embodiment is particularlyadapted to theheating of hydrocarbon oils to the high temperatures required for theirconversion. The invention permits the use of exceptionally high rates ofheat input to theoil undergoing treatment by applying direct radiantheat simultaneously and in substantially equal quantities to oppositesides of tubular elements comprising the fluid conduit. By employingsubstantially equal high rates of heating on opposite sides of the tubesless tube surface is required for the same amount of heating than whenone side of the tube is subjected to direct radiation and the oppositeside to reflected radiation and also, with this method of heating, thesubstantially equal heating conditions around the entire periphery ofthe tube eliminate internal stresses in the tube walls, due to widedifferences in temperature at different points in the tube walls.

In the present invention the oil is first passed through fluid conduitscomprising tube banks of the conventional convection heating and radiantheating type, while the succeeding portion of the fluid conduit, whereinsubstantially equal and high rates of heating are employed on oppositesides of each tubular element, is divided into a multiplicity of tubebanks and the heating conditions about each of these banks areindependently controlled so as to independently control the rate ofheating in each section of this portion of the fluid conduit. Thispractice permits the us of any type of heating curve regulated to suitthe requirements of the particular type of oil undergoing treatment. Inthis manner, for example, progressively increasing, progressivelydecreasing or substantially the same rate of heating may be employedthroughout that portion of the fluid conduit wherein a substantialproportion of the latent heat of vaporization and a major portion of thelatent heat of cracking is imparted to the oil, or any other desiredtype of heating curve may be employed in this portion of the fluidconduit. It is specifically within the scope of the invention to utilizeone or more of said separate sections of the fluid conduit as a soakingzone wherein the oil previously heated to the desiredconversiontemperature may be maintained at or near this temperature under-thedesired pressure conditions for a predetermined time. This type ofheating curve has been found particularly desirable in the treatment oflight distillates such as straight-run gasoline, naphtha, kerosene orkerosene distillate and the like for the production of high yields ofmotor fuels of high anti-knock value.

As another special feature of, the invention, each separate section ofthat portion of the fluid conduit wherein direct radiant heating isemployed on opposite sides of the tubes preferably in series, whendesired, but'preferably adjacent tubes in the same row are connected inseries and the different rows are connected in parallel so that separateand substantially equal streams of the same oil may pass simultaneouslythrough the two parallel rows whereby each stream is subjected tosubstantially'equal heating conditions. This practice permits high ratesof feed through the heating coil, permitting high charging capacitieswithout excessive pressure drop, due to friction through the fluidconduit. The preceding portions of the heating coil may also be arrangedfor either series or parallel flow, as desired. I

It is within the scope of the invention to utilize conventional methodsof heating in conjunction with the improved method above describedwhereby opposite sides of tubes in adjacent parallel rows are subjectedto uniform heating by direct radiation. Such conventional methods mayinvolve the use of separate banks of fluid conduits employing heating byconvection, heating by direct application of radiant heat on one side ofthe tubes and by the application of reflected radiant heat on theopposite side of the tubes, et cetera. The use of such methods are,however, not to be considered a limiting feature of the inventionalthough they are included in the following more detailed description ofthe inand 8, extending between the end walls 3 and 4 and from the roof 5to a point somewhat above the floor of the furnace, divide thecombustion zone of the furnace, in the case illustrated, into three maincombustion and heating sections designated in the drawings as 9, II) andI I. The partitions I and 8 each comprise, in the case illustrated,adjacent parallel walls with space provided therebetween for asupporting steel structure, (not shown). It is also within the scope ofthe invention to circulate all or any desired portion of the airrequiredfor combustion within the furnace through the spaces providedbetween the adjacent walls of partitions I and 8 to cool the walls andpreheat the air, although well known means whereby this may beaccomplished are not shownin the drawings.

Burner blocks I2 containing firing ports I3,-

located within the roof of the furnace, one set of such blocks adjacenteach side wall and on opposite sides of each partition wall, as shown,provide for the admission of combustibles into sections 9, I0 and II ofthe furnace, fuel of any desired form such as oil, gas or pulverizedsolid being supplied through burners I 4 of any suitable type equippedwith suitable control valves I4. Steam for assisting atomization of thefuel and/or. a portion of the air for combustion may be supplied throughburners I4, a major portion of the air for combustion preferably beingsupplied, however, through ducts i5, as will be later more fullydescribed. In the preferred embodiment of the invention, as illustratedin the drawings, the firing ports I3 and the burner block I2 areinclined slightly from the vertical in order to direct the flamesagainst the side walls I and 2 and opposite sides of the partition wallsI and 8 and the drawings also illustrate how the central portion-0f theroof above each of the sections 9, I9 and II may be depressed, asillustrated at points I It in the drawings, providing small combustionzones l7 beneath each row of firing ports to allow mixing and partialcombustion of the combustibles, prior to their admission into thecombustion and heating zones 9, l0 and II.

Preferably, combustion is substantially completed in sections 9, I0 andI I of the furnace and the hot combustion gases pass from these zonesalong the floor of thefurnace in the space I81 provided between thefloor and the partitions I and 8 and side wall Zemerging therefrom toenter the convection heating section I9 of the furnace, from which thecombustion products:

pass through ducts 20 and manifold 2| to an air preheater 22, of anysuitable form, whereby air for combustion within the furnace ispreheated by indirect contact with the combustion products, and thelatter finally pass from preheater 22 through flue 29 toa stack (notshown) Air is supplied to preheater 22 by means of a suitable fan orblower (not shown) through duct 24 and the preheated air, having passedthrough the preheater in direct contact with the flue gases from thefurnace, is discharged therefrom through header duct 25 to the branchducts 26, controlled by dampers 21 and, by means of ducts 26 and ductsI5, controlled by dampers 28, the preheated air is supplied in regulatedquantities to each of the firing ports I3 and, together with the fuelfrom burners I4, to the combustion 4 zones of the furnace, as alreadyindicated.

- time factor.

the combustion and heating zones ,9, III and II. Adjacent tubes inalternate rows are preferably staggered, as illustrated in the drawings,in order that the horizontally projected surfaces from adjacent sides ofthe tubes in adjacent rows are not shielded by tubes in the adjacentrow, opposite sides of each tube being exposed to direct radiation fromthe side or partition walls and from the materials undergoingcombustion.

Another portion of the fluid conduit, here illustrated, whereinconventional heating methods are employed, comprises a' singlehorizontal row 32 of horizontally disposed tubes 33 located adjacent thefloor 6 in the space I8 provided between the bottom of partitions 'I and8 and side wall 2 and the floor 6. These tubes are exposed on one sideto direct radiation from the materials undergoing combustion in sections9, I9 and II of the furnace and on the opposite side to reflectedradiant heat from the floor 6.

Another bank 34 of tubes 35 located in convection zone I9 of the furnaceserves to extract available convection heat from the combustion gases,in a conventional manner, prior to their passage from the furnace to theair preheater 22, as previously described.

The dotted lines passing through the tubes of the various sections 29,,30, 3| and 32 of the fluid conduit indicate one preferred path of travelfor the oil through the fluid conduit and the arrows on these linesindicate the general direction of flow therethrough. It will be notedthat, in the case illustrated, the oil enters the convection heatingbank 34 and is split into two streams each of which flows through anequal number of tubes in this bank and the general arrangement of .thetubes through which each stream flows is the same so that each stream issubjected to equal heating. The oil combined into one stream then passesthrough each tube 33 of row 32 in succession in a general directionconcurrent to the path of flow of the combustion gases. The stream ofheated oil leaving row 32 is again split into two equal streams whichpass in parallel through the adjacent rows 29 and30 of tubes 3| inseries, passing through each of the combustion and heating sections 9,I0 and I I counter-current to the general direction of the flame and thepath of travel of the combustion gases.

As an example of one method of operation with the flow of oil throughthe fluid conduit, as illustrated and above described, the oil is firstpreheated in tube bank 34 by convection heat recovered from the furnacegases and is then subjected to a progressively increasing rate ofheating in tube bank 32, which is supplied primarily with nascentradiant heat on one side and reflected radiant heat on the other, andthen passes through tube banks 29 and 30 in sections II, II] and 9 ofthe furnace in the order named wherein a high rate of heating isobtained on opposite "sides of each tube by direct radiation from theflames and from the refractory walls of the furace. The oil may, forexample, be brought to or near the desired maximum conversion tempera-,ture in section II of the furnace, in which case thatportion of thefluid conduit in sections 9 and It serves as a soaking zone wherein theoil may be maintained at or near the maximum conversion temperatureduring its passage there-- through in order to give the desiredconversion In case of an operation of this nature milder heatingconditions may ordinarily be employed in sections 9 and II) of thefurnace than in section I l as it is only necessary to maintain theattained temperature of the oil in sections 9 and I0. It will beapparent, however, that it is an inherent feature of the invention tomaintain substantially the same heating conditions in sections 9, illand II or to vary the heating conditions in the respective section toany desired degree.

It will be further understood that the invention is not limited to thespecific form of apparatus illustrated nor to the specific flow of fluidthrough the heating coil which has been illustrated and described. As anexample of various modifications of the furnace structure and the flowthrough the heating coil which may be employed within the scope of theinvention, although not illustrated, the furnace may, when desired, befired from the bottom instead of from the top in which case the tube row32, if employed, is located adjacent the roof of the furnace and theflow of oil through the tube bank 34, if employed, may be in either anupward or downward direction.

The various sections of the fluid conduit may be connected in anydesired sequence and the flow in any portion of the fluid conduit may bein any desired direction. The fluid undergoing treatment may flowthrough the adjacent rows 29 and 30 of any or all of the tube banks insections 9, i and II of the furnace either in series or in parallel andthis is also true with respect to the tubes in the convection heatingbank 34, Tube bank 32 may also be arranged for the passage of twostreams therethrough, when desired, so that split flow may be employedin this section as well as in the other portion of the fluid conduit. Itwill also be understood that one or any number of a plurality ofcombustion and heating sections such as 9, ill and ii may be employedand that the heating conditions in each of such zones are independentlycontrolled. As another possible modification of the furnace, (not shown)more than a single row of tubes similar to row 32 may be employedadjacent the floor of the furnace and, when desired, this portion of thefluid conduit may be replaced or augmented by a row or rows of tubesplaced adjacent the roof and floor of an elongated tunnel or flueconnecting zone l8 with zone i9.

I claim as my invention:

1. In a furnace for heating hydrocarbon oils comprising a main furnacestructure having side walls, end walls, a roof and a floor, thecombination with partition walls extending between said sides from nearthe floor to the roof of the main furnace structure dividing the sameinto a plurality of separate combustion and heating zones, means forindependently supplying combustibles to each combustion zone, means forremoving combustion gases' from each combustion zone and passing thesame through a convection heating zone to a stack, a fluid conduitlocated within said convection heating zone and supplied with availableconvection heat from said combustion gases, a communicating fluidconduit located adjacent the floor of the furnace directly beneath saidcombustion zones and comprising heating and combustion zones to directradiation from flames.

2. In a furnace for heating hydrocarbon oils comprising a main furnacestructure having side walls, endwalls, a roof and a floor, thecombination with partition walls extending between said sides from nearthe floor to the roof of the main furnace structure dividing the sameinto a plurality of separate combustion and heating zones, means forindependently supplying combustibles to each combustion zone, means forremoving combustion gases from each combustion zone and passing the samethrough a convection heating zone to a stack, a fluid conduit locatedwithin said convection heating zone and supplied with availableconvection heat from said combustion gases, a communicating fluidconduit located adjacent the floor of the furnace directly beneath saidcombustion zones and comprising horizontally disposed tubes heated onone side by direct radiation from the combustion gases and on theopposite side by reflected radiation from the floor, anothercommunicating fluid conduit comprising a pair of parallel vertical rowsof horizontal tubes in each combustion and heating zone, the tubes ofone of said rows being staggered with respect to the tubes of the otherrow, and means for subjecting opposite sides of each tube in saidheating and combustion zones to direct radiation from flames.

3. A process for heating fluid hydrocarbons to conversion temperaturecomprising passing the fluid hydrocarbons in a restricted stream througha heating coil embracing serially connected tubular elements disposedsubstantially in a common vertical plane intermediate a pair of parallelheat radiant walls substantially parallel to said plane and forming oneach side of the heating coil a combustion zone substantially free ofheat absorbing elements intermediate the walls and heating coil,projecting flames into said combustion zones on opposite sides of saidcoil and directing the flames angularly away from the coil and towardsaid walls so as to impart a high heat radiating capacity to asubstantial portion of each of said walls, and so controlling thegeneration and projection of flames into said combustion zones as tosubstantially uniformly heat the opposite sides of any given portion ofsaid heating coil.

4. A process for heating fluid hydrocarbons to conversion temperaturecomprising passing the fluid hydrocarbons in a restricted stream inseries through a plurality of tube banks, each tube bank embracing aplurality of series-connected substantially parallel tubular elementsdisposed in acommon vertical plane intermediate a pair of parallel heatradiating walls substantially parallel to said plane and forming on eachside of each tube bank a combustion zone substantially free of heatabsorbing elements intermediate the walls and tube banks, projectingflames into said combustion zones on opposite sides of each tube bankand directing the flames angnlarly away from said tube banks and towardsaid Walls so as to impart a high heat radiating capacity to asubstantial portion of each of said walls, and so controlling thegeneration and projection of flames into said combustion zones as toheat substantially uniformly the opposite sides of any given portion ofsaid tube banks.

5. A process for heating fluid hydrocarbons to conversion temperaturecomprising passing the fluid hydrocarbons in a restricted stream inseries through a plurality of tube banks, each tube bank embracing aplurality of series-connected substantially parallel tubular elementsdisposed in a common vertical plane intermediate a pair of parallel heatradiating walls substantially parallel to said plane and forming on eachside of each tube bank a combustion zone substantially free of heatabsorbing elements intermediate the walls and tube banks, projectingflames into said combustion zones on opposite sides of each tube bankand directing the flames angularly away from said tube banks and towardsaid walls so as to impart a high heat radiating capacity to asubstantial portion of each of said walls, and so controlling thegeneration and projection of flames into said combustion zones as toheat substantially uniformly the opposite sides of any given portion ofsaid tube banks, and varying the heat applied to the respective tubebanks to obtain the requisite heating curve for the fluid hydrocarbonsbeing heated.

6. A process for heating fluid hydrocarbons to conversion temperaturecomprising passing the fluid hydrocarbons through elongated tubescomprised in a tube bank embracing two adjacent parallel rows ofsubstantially parallel tubes, the tubes of one row being staggered inrespect to the tubes of the adjacent row, the tubes of each row lyingsubstantially in a common vertical plane, said tube bank being disposedintermediate 3, pair of parallel heat radiant walls substantiallyparallel to said planes, forming on each side of said tube bank acombustion zone substantially free of heat absorbing elementsintermediate the walls and tube bank, projecting flames into saidcombustion zones on opposite sides of said tube bank and directing theflames angularly away from the tube bank and toward said walls so as toimpart a high heat radiating capacity to a substantial portion of eachof said walls, and so controlling the generation and projection offlames into said combustion zones as to substantially uniformly heat theopposite sides of any given portion of said tube bank.

7. A process for heating fluid hydrocarbons to 1 conversion temperaturecomprising passing the fluid hydrocarbons serially through elongatedtubes embraced in a plurality of tube banks, each' tube bank comprisingtwo adjacent parallel rows of substantially parallel tubes, the tubes ofone row being staggered in respect to the tubes of the adjacent row, thetubes of each row lying substantially in a common vertical plane, eachtube bank being disposed intermediate a pair of parallel heat radiantwalls substantially parallel to said planes, forming on each side ofeach tube bank a combustion zone substantially free of heat absorbingelements intermediate the walls and tube bank, projecting flames intosaid combustion zones on opposite sides of each tube bank, directing theflames angularly away from said tube banks and toward said walls so asto impart a high heat radiating capacity to a substantial portion ofeach of said walls, and so controlling the generation and projection offlames into said combustion zones as to substantially uniformly heat theopposite sides of any given portion of said tube banks.

8. A process for heating fluid hydrocarbons to conversion temperaturecomprising passing the fluid hydrocarbons serially through elongatedtubes embraced in a plurality of tube banks, each tube bank comprisingtwo adjacent parallel rows of substantially parallel tubes, the tubes ofone row being staggered in respect to the tubes of the adjacent row, thetubes of each row lying substantially in a common vertical plane, eachtube bank being disposed intermediate a pair of parallel heat radiantwalls substantially parallel to said planes, forming on each side ofeach tube bank a combustion zone substantially free of heat absorbingelements intermediate the walls and tube bank, projecting flames intosaid combustion zones on opposite sides of each tube bank, directing theflames angularly away from said tube banks and toward said walls so asto impart a high heat radiating capacity to a substantial portion ofeach of said walls, and so controlling the generation and projection offlames into said combustion zones as to substantially uniformly heat theopposite sides of any given portion of-

